Timing device of the resettable and variable type



Dec. 11, 1956 N. F. THOMPSON 3RD., ETAL 2,773,548

TIMING DEVICE OF THE RESETTABLE AND VARIABLE TYPE Filed April 22, 1954United States PatentO TIMING DEVICE or THE RESETTABLE AND VARIABLE TYPEApplication April 22, 1954, Serial No. 424,964

7 Claims. (Cl. 161-1) This invention relates to timers in general, andto variable timers of the resettable kind in particular.

The timer with which the present invention is concerned is of the typeshown and described in the copendingapplication of Norman P. Thompson,Serial No. 424,618, filed April 21, 1954. This prior timer is designedto form a part of or be associated with a device whose period ofoperation is to be selectively controlled. In the specific example givenby way of illustration in the aforesaid application, the timer forms apart of a bread toaster to control the duration of the toastingoperation, although the timer may obviously serve to control the periodof operation of a great variety of other devices. In this prior timer, atiming element in the form of a reciprocating rack is advanced from astarting position by a suitable power drive to cooperate with apivotally mounted operating member, moving the latter into a terminalposition from a set position at the completion of a selected timeinterval of operation. Movement of the operating member into suchterminal position is employed to mechanically actuate the device underthe control of the timer, and simultaneously to interrupt the drive tothe timing element so that it may return to a starting position and beready for a new cycle of operation. Selection of the duraton of thetiming cycle of operation is afforded by providing on the operatingmember an adjustable'cam with which the timing element coacts to movethe member to its terminal position. In the prior device, this cam iscarried by the operating memberfor movement radially of the pivot axisof the latter, and cooperating with the cam is a pivoted shifter armwhich may manually be turned to move the former into an infinite numberof adjustments on the operating member. Moreover, the cam, itsadjustment range on the operating member, and the timing element are socoordinated that the cam may be moved by the shifter arm to causeimmediate movement of the operating member to its terminal position atany time and, hence, permit premature termination of any operating cycleof previously selected duration.

1 It is an object of the present invention to provide a variable timerof this type of which both the timing element and the adjustable elementon the operating member are cams which may be designed to achieve mostany desired movement of the operating member to its terminal position,such as substantially uniform motion, approximate harmonic motion,variable motion and snap motion, for instance, as well as a variety ofother motions.

It is another object of the present invention to provide a variabletimer of this type of which the cam element on the operating member ispivotally mounted thereon and is angularly adjustable, thereby toachieve an exceptionally wide range of possible operating cyclevariation with a minimum of bulk.

It is a further object of the present invention to pro vide a singlebearing for the pivotal support of the operating member and also for thejournal support of a pinion ,coaxially of the pivot support of theoperating 2,773,548 Patented Dec. 11,

member, and to further provide the pivoted cam element as the operatinginember with a gear segment which is in mesh with the aforesaid pinion,thereby achieving not only exceeding structural simplicity of the timerand ready assembly of these parts with the rest of the timer, but alsoaccurate and immediate response to any turn of the pinion of the camelement in its adjustment on the operating member.

Further objects and advantages will appear to those skilled in the artfrom the following, considered in conjunction with the accompanyingdrawings.

In the accompanying drawings, in which certain modes of carrying out thepresent invention are shown for illustrative purposes:

Fig. 1 is a side elevation of a variable timer embodying the presentinvention;

Fig. 2 is an end elevation of the same timer as viewed in the" directionof the arrow 2 in Fig. 1;

Fig. 3 is another side elevation of the timer as viewed in the directionof the arrow 3 in Fig. 2;

Fig. 4 is another end elevation of the timer as viewed in the directionof the arrow 4 in Fig. 1;

Fig. 5 is a section through the timer as taken on the line 55 of Fig. 4;

Figs. 6, 7 and 8 are fragmentary side elevations of the timer, showingcertain parts thereof in different operating positions; and

Fig. 9 is an enlarged fragmentary section through the timer as taken onthe line 9-9 of Fig. 1.

Referring to the drawings,'the reference numeral 20 designates a timerwhich for purposes of illustration, is adapted to control the operatingcycles of a bread toaster. As shown here, the timer comprises anoperating member or trigger 22, as it will be referred to hereinafterfor convenience, a timing element 24, a power drive 26 for the timingelement (Figs. 2, 4 and 5), and a drive control 28, all of which areprovided in or on a timer frame 30. The timer frame 30 comprises, inthis instance, opposite end plates 32 and 34 which are held in spacedparallel relation by a plurality of pillars 36.

The trigger 22 is in the form of an arm which, as shown in Fig. 9, ispivotally mounted on a diametrically reduced portion 37 of a bearing 38on the frame plate 32. The trigger 22 is normally urged by a returnspring 40 into a maximum set position (Figs. 1 and 7) in which a bentlug 41 on the trigger 22 bears against one end of an arcuate slot 42 inthe frame plate 32. The return spring 40 is anchored with its ends onthe frame plate 32 and trigger 22, respectively. The trigger 22 isturned into its set position to start an operating cycle of the timer,as will be more fully described hereinafter. Conversely, an operatingcycle is terminated when the trigger 22 is shifted from its set positionin Figs. 1 or 7 into its terminal position in Figs. 6 or 8 by the timingelement 24 in a manner described hereinafter.

In the present example, the trigger 22 is, through intermediation of alever 44, operatively connected with a latch bar 46 on the usual toasterrack (not shown). The lever 44 may conveniently be pivoted at 48 on atoaster frame (not shown) in which the present timer is suitably mountedand the aforementioned toaster rack is customarily depressible fortoasting purposes and released for spring-return to a raised position atthe end of a toasting cycle. In this instance, the timer 20 isconveniently mounted, by lugs 49 on its end plates 32 and 34, on a plate51 of the toaster frame.

The lever 44 has two arms 52 and 54 which carry a follower pin 56 and alatch pin 58, respectively. The follower pin 56 projects into thebifurcated end 60 of the trigger 22, while the latch pin 58 projectsinto a longitudinal slot 62 in the latch bar 46. The slot 62 in thelatch bar 46 has a straight portion 64 and an oifset por- (J tion 66,and the latch bar is normally urged into its uppermost position (Fig. 6)due to its explained connection with the spring-urged toaster rack.However, the latch bar 46 will, in the depressed position of the toasterrack, prevent the pop-up of the latter when the trigger 22 is in anyposition other than its terminal position and holds the lever 44 so thatits latch pin 58 is somewhere in the offset slot portion 66 and lockswith the latch shoulder 70 on the latch bar (Fig. 1). When the trigger22 is thereafter shifted into its terminal position (Figs. 6 and 8) thelever 44 will also be shifted to bring its latch pin 58 from interlockwith the latch shoulder 70 into alignment with the straight slot portion64 in the latch bar 46, whereupon the latter and the toaster rack arereleased from their depressed position and permitted to pop up. Asuitable switch (not shown) for the control of the usual heatingelements in the toaster may automatically be opened in any suitablemanner on the pop-up of the toaster rack to terminate a toasting cycle.In depressing the toaster rack by any of the conventional means providedfor that purpose, the latch bar 46 is lowered sufficiently to permit thelever 44 and the trigger 22 to swing into the respective positions shownin Figs. 1 and 7 under the urgency of the trigger spring 40, returningthereby the latch pin 58 on the lever 44 into interlock with the latchshoulder 70 on the latch bar 46 and, hence, preventing the pop-up of thetoaster rack until the trigger 22 is again shifted into its terminalposition. The aforementioned switch for the heating elements in thetoaster may automatically be closed in any suitable manner on depressionof the toaster rack to start a toasting cycle.

The timing element 24 is, in the present instance, in the form of a camon a staff 72 which is suitably journalled in the end plates 32 and 34of the timer (Fig. 4). A torsion spring 74, which is anchored with itsends to the frame plate 34 and an anchor plate 76 on the staff 72 (Fig.4), normally urges the latter in a direction to return the timingelement 24 into a starting position in which the same bears against astop 78 on the frame plate 32 (Figs. 1, 7 and 8).

The power drive 26 of the timing element 24 comprises a reduction geartrain 80 which is driven by any suitable prime mover or power source,such as a synchronous motor 82, for instance (Figs. 2, 4 and The geartrain 80 has the previously mentioned output shaft 72 which carries thetiming element 24. The motor 82 is suitably mounted at 86 and 88 in thetimer frame 30, and its rotor shaft 90 carries a gear 92 which forms apart of the gear train 80. Starting from the motor 82, the gear train 80has successive stages of speed reduction in the gear parts 92 and 94,.96 and 98, 100 and 102, 104 and 106, 108 and 110, and 112 and 114. Asalready mentioned, the gear 92 is carried by the rotor shaft 90 of themotor 82. The next succeeding sets of unitary gears 94, 96 and 98, 100are carried by suitably journalled staffs 116 and 118, respectively, inthe timer frame 30. The unitary gears 102, 104 of the next set arefreely rotatable on a fixed staff 120 in the timer frame 30. The unitarygears 106, 108 of the next set are carried by a staff 122 which is notonly journalled in the timer frame but is also axially movable thereinfor a purpose described hereinafter. The unitary gears 110, 112 of thenext set are freely rotatable on the same fixed staff 120 on which thegears 102, 104 of the previously mentioned set are also freelyrotatable. Finally, the end gear 114 of the train is carried by theoutput shaft 72. Any suitable means, such as the collars 124 and 126 maybe provided on the fixed staff 120 in order to prevent axial motion ofthe gear sets 102, 104 and 110, 112 thereon.

The gear train 80 is also provided with a normally engaged clutch whichis disengaged to interrupt the gear train 80 at the end of eachoperating cycle and between successive operating cycles, and which isengaged during each operating cycle. This clutch is, in the presentinstance, constituted by the axially immovable gear and the gear 108 onthe axially shiftable staff 122, and Fig. 2 shows this clutch engaged byvirtue of the meshed relation of these gears. The staff 122 may beshifted to the right as viewed in Fig. 2 to demesh the gear 108 thereonfrom the gear 110 on the fixed staff without demeshing the gears 106 and104, and thereby interrupt the gear train.

The shiftable staff 122 is normally urged, by means of a leaf-typespring 130 on the frame plate 34 (Fig. 2), into clutch-engaging positionin which a collar 132 thereon bears against the frame plate 32 and thegears 108 and 110 are in mesh with each other. The staff 122 is shiftedat the proper times into clutch disengaging position, to demesh the gear108 from the gear 110 and thereby interrupt the gear train, by means ofthe aforementioned control 28 which is in the form of a punched-out camlug on the trigger 22. This cam lug is so arranged (Fig. 2) as todepress the adjacent end 136 of the staff 122 and demesh the gear 108from the gear 110when the trigger 22 is shifted into its terminalposition to terminate an operating cycle (Figs. 6 and 8), and to releasethe end 136 of the staff 122 and permit the latter to be spring-urgedinto its clutch-engaging position for reme'sh'of the gear 108 with thegear 110 (Fig. 2) when the trigger is shifted from its terminal positiontoward its set position for starting an operating cycle. The timerdescribed so far is in most essential respects like the timer shown anddescribed in the aforementioned copending application Serial No.424,618, except that the present timing element 24 is a cam.

The instant timer 20 is also of the variable type, i. e. its operatingcycles may be of. variable duration. To this end, the timing element 24does not directly cooperate with the trigger 22, but acts throughintermediation of an adjustable cam element 140 on the trigger, inshifting the latter into its terminal position for the termination of anoperating cycle. It is this cam element 140 and its adjustability on thetrigger 22, coupled with the cam form of the timing element 24, whichform the major part of the present invention. The cam element 140 ispivotally mounted at 142 on the trigger 22. For its angular adjustmenton the trigger 22, the cam element 140 is provided with a gear segment144 which is in mesh with a pinion 146 (Figs. 1, 2 and 9). The pinion146 has a shank 148 which is journalled in the aforementioned hearing 38on which the trigger 22 is pivoted coaxially of the pinion 146 (Fig. 9).The shank 148 of the pinion 146 is retained in the bearing 38 by meansof a disc 150 which is interposed between the frame plate 32 and a snapring 152 on the shank 148. The disc 150 is a spring disc which holds amounted flange 154 on the pinion 146 in engagement with the adjacent endof the bearing 38 with sufficient friction to resist rotation of thepinion 146 unless the same is manually turned with some force forintended angular adjustment of the cam element 140 on the trigger. Thepinion 146 is also provided with a slotted hub 158 for connection with aknob (not shown) with which to turn the pinion 146 whenever the camelement 140 is to be angularly adjusted on the trigger.

The element 140 is provided with a contoured periphery forming a camsurface 160 which confronts and is in operative alignment with thetiming element 24, and is engaged by and compelled to follow the latteron its power drive in an operating cycle until the trigger 22 is turnedto its terminal position for the termination of the operating cycle. Thegap (Fig. 7) between the timing element 24 in its starting position andthe cam element 140 in the maximum set position of the trigger 22, atthe start of an operating cycle, will vary with the angular adjustmentof the cam element on the trigger, with the result that the ensuingoperating cycle will also vary with the adjustment of the cam element.

The angular adjustment range of the cam element-140 on the trigger 22isnot so limited asto'leavea gap between it and the timing element'24every time the trigger is shifted from its terminal position for thestart of an operating cycle, neither may the trigger be shifted 'all'theway to its maximum set position (Figs. 1 and 7) for the start of everyoperating cycle. Thus, the cam element 140 may be adjusted on thetrigger to the extent shown inFig. 1, for instance, such that the formerwill, on shifting the latter into its maximum set position, engage thetiming element 24 substantially in its starting position, with theresult that the ensuing operating cycle will be of considerably shorterduration than that resulting from the adjustment or setting of the camelement in Fig. 7. The cam element 140 may be adjusted even further,clockwise from the position shown in Fig. 1, so that the same willengage the timing element 24 in, or substantially in, its startingposition when the trigger 22 is shifted from its terminal position intoa set-position which is anywhere between the latter position and itsmaxmum set position, with the result that the ensuing operating cyclewill be even shorter in duration than that resulting. from the exemplaryadjustment of the cam element in Fig. 1.

It thus follows from the preceding that the angular adjustability of thecam element 140 on the trigger 22 affords an infinite number of timeinterval variations Within a wide range. The cam element 140 may,through manipulation of the aforementioned knob on the pinion 146, beadjusted for a desired time interval before the same is started, or maybe adjusted during an operating cycle to vary the same as desired.Furthermore, the cam element 140, its angular adjustment range on thetrigger 22, and the timing element 24, are so coordinated that anystarted operating cycle may instantaneously be terminated at any time.In this connection, let it be assumed that an operating cycle of maximumpossible duration has been started, and that it is desired to terminatethe cycle immediately after its start. This may readily be accomplishedby merely turning the cam element 140 into the position shown in Fig. 8so that the same will react with the timing element 24 and shift thetrigger into its terminal position before the timing element has beendriven through an appreciable angular distance, if any, from itsstarting position. Since an operating cycle of maximum possible durationmay instantaneously be terminated immediately after its start, itfollows that all possible selected time intervals of timer operation mayinstantaneously be terminated at any time aftertheir start.

Following is a description of a cycle of operation of the instant timerin connection with the toaster with which it is associated in thepresent example. After angularly adjusting the cam element140 on thetrigger 22, to the extent shown in Fig. 1, for instance, for the desiredduration of the time interval of timer operation to follow, theoperating cycle is started by depressing the toaster rack, with theresult that the trigger 22 is permitted to shift into the set positionshown in Fig. 1 under the urgency of its return spring 40, and thetoaster rack will for the duration of the timer cycle be held in itsdepressed position by virtue of the interlock of the latch pin 58 on thelever 44 with the latch shoulder 70 on the latch bar 46. Immediatelyafter the trigger 22 leaves its terminal position in its shift towardits set position, the cam lug 28 thereon withdraws from the depressedstaff 122 (Fig. 2) and permits the latter to be shifted by the leafspring 130 into its clutch-engaging position to bring the gear 108thereon into remesh with the gear 110 and thereby restore the gear train80 and impart it drive to the timing element 24 for the advance of thelatter from its starting position (Fig. 1). In this exemplary operatingcycle the timing element 24 will immediately on its advance fromstarting position cooperate with the cam element 140 in shifting thetrigger 22 from its set position toward and into its terminal position.The trigger 22 will, in the course of its advance toward its terminalposition, rock the lever 44 so that its latch pin 58 will move on thelatch shoulder 70 closer toward alignment with the straightslot portion64 in the latch bar 46. When the timing element 24 finally shifts thetrigger 22 into its terminal position, the latch pin 58 on the leverwill be in alignment with the straight slot portion 64 in the latch bar46 and permit the latter and the associated toaster rack to pop. up andthereby terminate an operating cycle of the toaster. Further, when thetrigger 22 reaches its terminal position the cam lug 28 thereon willhave depressed the staff 122 sufiiciently to demesh the gear 108 fromthe gear 110 and interrupt the gear train to terminate the timingoperation and permit the spring 74 to return the timing element 24 toits starting position.

It follows from thepreceding that the gears 114, 112 and 110 of thetrain will be driven, counter to their normal drive, on thespring-return of the timing element 24 to its starting position, whilethe remaining gears of the train will not interfere with the return ofthe timing element regardless of whether they are driven by the motor 82between successive operating cycles, or are at rest if the motor shouldbe shut off in any suitable manner on the pop-up of the toaster rack.The few reduction gears 114', 112 and 110, which are reversely driven bythe timing element 24 on its spring-return to starting position,constitute an effective brake for the timing element so that the samewill not be forcefully snapped back into its starting position but willrather gradually return thereinto. This hesitancy and delay in returningthe timing element 24 to its starting position does not in the leastinterfere with desired rapid repeatcycle performance of the timer forthe following reason. The trigger 22 remains in its terminal positionuntil the next operating cycle is started and the gear train 80 remainsinterrupted until then, wherefore the timing element 24 has availablethe entire period between successive cycles of the timer to return toits starting position. The gradual, rather than a quite sudden, returnof the timing element 24 to its starting position not only protects itand the parts connected therewith from harmful jarring and undue wear,but also assures that the timing element is in its starting position andrests against the stop 78 at the time the next cycle is started and,hence, assures high accuracy of the duration of the next operating cyclein conformity with the setting of the timer.

Due to the explained frictional resistance of the pinion 146 againstturning, the gear segment 144 of the cam element will slightly roll onthe pinion 146 when shifted from and into its terminal position, as willbe readily understood. However, this rolling of the gear segment 144 onthe pinion 146 will not in any way change any operating cycle for whichthe timer has been set prior to the start of the cycle. Thus, thisrolling of the gear segment 144 on the pinion 146 will cause during ashift of the trigger from its terminal position into any set position aslight counterclockwise shift of the cam element 140 on the trigger(Fig. 1) which will continue as a clockwise shift of the same magnitudeduring the following shift of the trigger into its terminal position, sothat the angular shift of the cam element will be canceled when thetrigger returns to its terminal position and the time interval ofoperation then terminated will be exactly of the duration for which thetimer was preset.

The formation of both the timing element 24 and the adjustable element140 as cams is highly advantageous in that they may be designed toachieve most any desired movement of the trigger to its terminalposition from the set position, whereby substantially uniform motion,approximate harmonic motion, variable motion and snap motion, forinstance, may be obtained. Further, the pivotal arrangement of the camelement on the trigger and its angular adjustability thereon areinstrumental in achieving an exceptionally wide range of timing intervalvariation with a minimum of bulk. Also, the instant arrangement ofmounting the trigger 22 and pinion 146 on and in the single bearing 38(Fig. 9) and providing the pivoted cam element on the trigger with agear segment for direct mesh with the aforesaid pinion makes forstructural simplicity of the timer as well as ready assembly of theseparts with the rest of the timer. Moreover, the direct mesh of the gearsegment of the pivoted cam element on the trigger with the pinion 146and the journal support of the latter coaxially of the pivoted triggersupport makes for accurate and immediate response of the cam element inits adjustment to any turn of the pinion at any time.

The invention may be carried out in other specific ways than thoseherein set forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

What is claimed is:

l. A variable timer, comprising a pivoted operating member forcontrolling the operation of a device being timed by the timer, saidoperating member being turnable into and from a terminal position toterminate and Start, respectively, operating cycles of selectively timedduration; a gear segment pivoted on said operating member at a pointremote from the pivot axis of the latter; a pinion in mesh with saidgear segment and turnable about the pivot axis of said operating member;means for turning said pinion to adjust said gear segment relative tosaid operating member; a timing element normally urged in one directioninto a starting position, and movable in the opposite direction, fromits starting position through a distance varying with the adjustment ofsaid gear segment, to coact with the latter and turn said operatingmember into its terminal position; a power drive for moving said timingelement in said opposite direction at a predetermined rate; a clutchincorporated in said power drive; and means disengaging and reengagingsaid clutch in response to movement of said operating member into andfrom its terminal position, respectively.

2. A variable timer as set forth in claim 1, in which said gear segmenthas a contoured periphery forming a cam surface .with which said timingelement coacts in turning said operating member into its terminalposition.

3. A variable timer as set forth in claim 1, in which said power drivehas an output shaft, and said timing clement is a cam carried by saidoutput shaft.

4. A variable timer as set forth in claim 1, in which said power drivehas an output shaft, said timing element is a cam carried by said outputshaft, and said gear segment has a contoured periphery forming a camsurface with which said cam coacts in turning said operating member intoits terminal position.

5. A variable timer as set forth in claim 1, in which said. gear segmenthas a contoured periphery forming a cam surface with which said timingelement coacts' in turning said operating member into its terminalposition,

said gear segment being adjustable to coact with said timing element inany position of the latter and turn said operating member into itsterminal position for instanteneous termination of an operating intervalof the timer at any time.

6. A variable timer, comprising a pivoted operating member forcontrolling the operation of a device being timed by the timer, saidoperating member being turnable into and from a terminal position toterminate and start, respectively, operating cycles of selectively timedduration; a gear segment pivoted on said operating member at a pointremote from the pivot axis of the latter; a pinion in mesh with saidgear segment and turnable about the pivot axis of said operating member;friction means to resist rotation of said pinion; manual means forturning said pinion to adjust said gear segment relative to saidoperating member; a timing element normally urged in one direction intoa starting position, and movable in the opposite direction, from itsstarting position through a distance varying with the adjustment of saidgear segment, to coact with the latter and turn said operating memberinto its terminal position; a power drive for moving said timing elementin said opposite direction at a predetermned rate; a clutch incorporatedin said power drive; and means disengaging and reengaging said clutch inresponse to movement of said operating member into and from its terminalposition, respectively.

7. A variable timer for controlling the operating time of a device,comprising a bearing; an operating member connected to the device to betimed, said member being turnablymounted on said bearing externallythereof for movement into and from a terminal position to terminate andstart, respectively, operating cycles of selectively timed duration; agear segment pivoted on said operating member; a pinion in mesh withsaid gear segment and journalled in said bearing for rotation about therotary axis of said operating member; spring means urging said pinionagainst said bearing frictionally to resist rotation of the former;manual means for turning said pinion to adjust said gear segmentrelative to said operating member; a timing element normally urged inone direction into a starting position, and movable in the oppositedirection, from its starting position through a distance varying withthe adjustment of said gear segment, to coact with the latter and turnsaid operating member into its terminal position; a power drive formoving said timing element in said opposite direction at a predeterminedrate; a clutch incorporated in said power drive; and means disengaging.and reengaging said clutch on movement of said operating member into andfrom its terminal position, respectively.

References Cited in the file of this patent UNITED STATES PATENTS2,609,044 Stanton Sept. 2, 1952

